• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.41-46
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• 1998

The purpose of the study was changed of Flood Characteristics in Down stream of Keum River by the Keum River Estuary Dam Construction. The water surface slope of Kuem river after the Keum River Estuary Dam construction was steeper then before. The flood control capacity increase after construction. But, Increasing sediment in Kuem river will be decreased flesh reservoir volume for yield irrigation.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.10
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• pp.581-590
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• 2017

For effective improvement of water quality in Seokmun reservoir, this study implemented various analyses including the tributary water quality and flowrate monitoring, contamination of sediment, investigation of pollution source, selection of priority management target tributary by stream grouping method. The COD concentration of the majority of tributaries in Seokmun reservoir watershed was relatively higher than BOD concentration. The concentration of water pollutants regardless of water quality parameters in Yeokcheon, Dangjincheon, Sigokcheon, Baekseokcheon, small stream in Jinkwanri and Janghangri were higher than the other tributaries. The pollution sources in the Seokmun reservoir watershed were mostly distributed in the population, livestock, and industry. The pollutants, which located in Yeokcheon, Dangjincheon, Baekseokcheon, and small stream in Janghangri selected as priority management target tributary, should be preferentially reduced for improving the water quality in Seokmun reservoir. As the evaluation results of water quality in Seokmun reservoir for the effect of water quality improvement according to various scenarios using water quality model, it was found that the water quality in Seokmun reservoir due to the construction of a wastewater treatment plant for management of pollutants in the watershed would be satisfied the class V of water environment standard in reservoir.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.2
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• pp.1-17
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• 2015

Ecological reservoir is a multifunctional space where provides the functions of retention, animal habitat and improvement of ecosystem health and landscape. The ecological reservoir of Anteo Eco Park located in Gwangmyeong-si has established to functions for water purification, maintenance of healthy aquatic ecosystem. Because the Anteo Eco Park is located in the site where nonpoint pollutant materials flow in, Anteo Eco Park has potential factors which aquatic ecosystem health deteriorates and damages the habitat of golden frog(Rana plancyi chosenica) which is restoration target species. Therefore, the purpose of this study is to suggest the plan to manage the variables which impede the right functions of aquatic ecosystem by understanding the causal loop diagram for the change of water quality environment and the interaction of predator-prey through system thinking. The results are as follows. First, the study showed that the individual number of golden frog which is an indicator species of Anteo Eco Park is threatened by snakeheaded fish, which is an upper predator. Therefore, balanced food chain should be hold to protect golden frog by capturing the snakeheaded fish which is individual number's density is high, and the monitoring management of the individual number for predator(snakeheaded fish)-prey(golden frog) should be performed. Second, the study represented that water pollution and carnification is caused by the sediment as the dead body of the large emergent vegetation in the winter cumulates as sediment. Ecological reservoir in Anteo Eco Park has been managed by eliminating the dead body of the large emergent vegetation, but the guideline for the proper density maintenance of vegetation community is additionally needed. Lastly, the study showed that aquatic ecosystem of Anteo Eco Park where is contaminated from the inflow of nonpoint pollutants affects the individual number's decline of golden frog and snakeheaded fish. Accordingly, the creation of a buffer area and a substitution wetland is needed in the periphery of the Anteo Eco Park to control the inflow of nonpoint pollutants including organic matters, nutrients and heavy metals. This study will be helpful that Anteo Eco Park improves the regional landscape and maintain healthy aquatic ecosystem space for the park visitors including local residents.

• Korean Journal of Ecology and Environment
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• v.38 no.3 s.113
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• pp.372-381
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• 2005

This study was conducted to test the efficiency of water quality improvement using the dissolved air flotation (DAF) technique in a shallow eutrophic reservoir. The application of DAF was followed by the addition of a chemical coagulant (poly aluminum chloride; PAC). The experiment was conducted in the mesocosm scale (wide ${\times}$ length ${\times}$ depth: 6 m ${\times}$ 6 m ${\times}$ 3 m). Suspended solids (SS) and volatile SS (VSS) concentration decreased by 54 ${\sim}$ 71% and 57 ${\sim}$ 79% of the initial concentrations, respectively. Total phosphorus and Chl- a concentration also decreased by 74 ${\sim}$ 92% and 54 ${\sim}$ 98%, respectively. BOD decreased by>86% while COD decrease ranged 29 ${\sim}$ 63%. Dissolved inorganic P (DIP) and dissolved total P (DTP) concentration decreased by 34 ${\sim}$ 88% and 62 ${\sim}$ 88%, respectively. After DAF application further onto the sediment, DIP-release rates from the sediment decreased by 17% (0.82 ${\to}$ 0.68 mg $m^{-2}$$day^{-1}$ in the oxic condition and 23% (2.27 ${\to}$ 1.76 mg $m^{-2}$$day^{-1}$) in the anoxic condition, compared to the release rate from the untreated sediment. DTP-release rate from both the oxic and anoxic sediments also decreased by 33% (5.62 ${\to}$ 3.78 mg $m^{-2}$$day^{-1}$) and 20% (6.23 ${\to}$ 4.99 mg $m^{-2}$$day^{-1}$), respectively. These results suggest that the DAF application both to the water column and onto the sediment be effective to improve water quality by removing particulate matters in the water column as well as reducing P-release from the sediment.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.2
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• pp.209-217
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• 2011

This study incorporate hydroacoustic sampling for bathymetry and sediment survey in Won Cheon reservoir, Suwon city, Korea. Bathymetric and sedimentation surveys were conducted using a echo sounder system and subbottom profiler in the reservoirs. Data were collected using echo sounder systems and subbottom profiler linked to a GPS, to maximize data accuracy and vessel use, and geo-referenced using a DGPS enabling the acoustic data to be used in a GIS. Echo sounder and subbottom survey data were merged within geographic information system(GIS) software to provide detailed visualization and analyses of current depths, pre-impoundment topography, distribution, thickness, and volume estimates of lacustrine sediment, and water storage capacity. These data and analyses are, necessary for development of long term management plans for these reservoirs and their watersheds.

• Geophysics and Geophysical Exploration
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• v.26 no.4
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• pp.199-210
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• 2023

The physical properties of rocks in reservoirs change after CO₂ injection, we modeled a reservoir with a transition zone within which the physical properties change linearly. The function of the Wolf reflection coefficient consists of the velocity ratio of the upper and lower layers, the frequency, and the thickness of the transition zone. This function can be used to estimate the thickness of a reservoir or seafloor transition zone. In this study, we propose a method for predicting the thickness of the transition zone using deep learning. To apply deep learning, we modeled the thickness-dependent Wolf reflection coefficient on an artificial transition zone formation model consisting of sandstone reservoir and shale cap rock and generated time-frequency spectral images using the continuous wavelet transform. Although thickness estimation performed by comparing spectral images according to different thicknesses and a spectral image from a trace of the seismic stack did not always provide accurate thicknesses, it can be applied to field data by obtaining training data in various environments and thus improving its accuracy.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.161-171
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• 2009

A 'continuous removal of organic matters (CROM) system' using a native freshwater bivalve in Korea Anodonta woordiana, was developed to determine its potential of controlling various sestons in eutrophic lake system, and to evaluate its effect on water quality improvement under consideration of sediment addition as habitat. We designed CROM experiments with four treatments: no mussels and no sediment (W, negative control), no mussels and sediment (WS, positive control), mussels and no sediment (WM), and mussels and sediment (WMS). The experiments were performed at the condition of 18${\sim}$25 L $h^{-1}$ of inflow, mussel density of 486.1 indiv. $m^{-2}$, and temperatures between 15 and $22^{\circ}C$ for 13 consecutive days. Physicochemical and biological parameters were measured at daily (10:00 am) intervals after the mussel addition. Results indicated that mussel stockings without addition of sediment effectively removed sestons (suspended solids and chlorophyll-a) at nearly same level over 80 percentage of the control during the study, while there were no differences in removal activities of sestons between with and without sediment (P>0.5). Therefore, it clearly suggests that CROM system using A. woordiana has a strong potential to control the seston in surface water of eutrophic lake.

• Journal of Environmental Impact Assessment
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• v.26 no.6
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• pp.553-562
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• 2017

In these days, agricultural reservoirs are considered as a useful resource for recreational purposes, tour and cultural amenity for vicinity communities as well as irrigation water supply. However, many of the agricultural reservoirs are showing a eutrophic or hyper-eutrophic state and high level of organic contamination. In particular, about 44.7% of the aged agricultural reservoirs that constructed before 1945 exceed the water quality criteria for irrigational water use. In addition to external loading, internal nutrient loading from bottom sediment may play an important role in the nutrient budget of the aged reservoirs. The objectives of this study were to characterize variations of thermal structure of a shallow M reservoir (mean depth 1.7 m) and examine the potential of internal nutrient loading by continuous monitoring of vertical water temperature and dissolved oxygen (DO) concentration profiles in 2015 and 2016. The effect of internal loading on the total loading of the reservoir was evaluated by mass balance analysis. Results showed that a weak thermal stratification and a strong DO stratification were developed in the shallow M Reservoir. And, dynamic temporal variation in DO was observed at the bottom of the reservoir. Persistent hypoxic conditions (DO concentrations less than 2 mg/L) were established for 87 days and 98 days in 2015 and 2016, respectively, during the no-rainy summer periods. The DO concentrations intermittently increased during several events of atmospheric temperature drop and rainfall. According to the mass balance analysis, the amount of internal $PO_4-P$ loading from sediment to the overlying water were 37.9% and 39.7% of total loading during no-rainy season in 2015 and 2016, respectively on August when algae growth is enhanced with increasing water temperature. Consequently, supply of DO to the lower layer of the reservoir could be effective countermeasure to reduce nutrient release under the condition of persistent DO depletion in the bottom of the reservoir.

• Korean Journal of Ecology and Environment
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• v.41 no.4
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• pp.431-440
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• 2008

Turbid water or suspended sediment is associated with negative effects on aquatic organisms; fish, aquatic invertebrate, and periphyton. Effects of turbid water on fish differ depending on their developmental stage and a level of turbidity. Low turbid water may cause feeding and predation rates, reaction distance, and avoidance in fish, and it could make fish to die under high turbidity and long period. Therefore, it is very important to find out how turbid water or suspended sediment can affect fish in domestic watersheds. The objectives of this study were 1) to introduce international case studies and their standards to deal with suspended sediment, 2) to determine acute toxicity in 4 major freshwater fishes, and 3) to determine in relation to adverse effect of macroinvertebrates and fish. Impacts of turbid water on fish can be categorized into direct and indirect effects, and some factors such as duration and frequency of exposure, toxicity, temperature, life stage of fish, size of particle, time of occurrence, availability of and access to refugia, etc, play important role to decide magnitude of effect. A review of turbidity standard in USA, Canada, and Europe indicated that each standard varied with natural condition, and Alaska allowed liberal increase of turbidity over natural conditions in streams. Even though acute toxicity with four different species did not show any fatal effect, it should be considered to conduct a chronic test (long-term) for more detailed assessment. Compared to the control, dominance index of macroinvertebrates was greater in the turbid site, whereas biotic index, species diversity index, species richness index, and ecological score were smaller in the turbid site. According to histopathological analysis with gills of macroinvertebrate and fishes, morphological and physiological modification of gills due to suspended sediments can cause disturbance of respiration, excretion and secretion. In conclusion, in order to maintain good and healthy aquatic ecosystem, it is the best to minimize or prevent impact by occurrence of turbid water in stream and reservoir. We must make every effort to maintain and manage healthy aquatic ecosystem with additional investigation using various assessment tools and periodic biomonitoring of fish.

• The Journal of Engineering Geology
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• v.23 no.2
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• pp.95-104
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• 2013

This study proposes an efficient management plan for improving the water quality of agricultural reservoirs. Hongdong reservoir is located in an area that includes farmland, forest, residential housing, and livestock farms. The levels of pollutants in Hongdong reservoir were investigated with the aim of improving the water quality in the reservoir. The potential concentrations of total nitrogen (T-N) and total phosphorus (T-P) in Hongdong reservoir were 1.06-3.67 and 0.52-1.12 $g/m^2-d$, respectively. An analysis of leaching characteristics was performed under anaerobic conditions for 72 hours at $20^{\circ}C$. The concentrations of T-P and $PO_4$-P were measured by general leaching for a set period. In the case of T-P, the leaching was measured by irregular leaching due to denitrification of nitrite nitrogen ($NO_2$-N) and nitrate nitrogen ($NO_3$-N). A very small amount of $NH_3$-N on nitrogen ($N_2$) was measured due to the low pH in the column, as a consequence of the anaerobic conditions.